What has been developed is a cryptoanalysis method for detecting secret data, such as a secret key, by measuring power or time consumed during an arithmetic operation of a cryptographic algorithm. Leakage of secret data for a cryptographic algorithm is sometimes called a “side channel”, and attacks via the side channel are sometimes called “side channel attacks”. The side channel attack can be broadly classified into a timing attack, a fault insertion attack, and a power analysis attack.
FIG. 1 is a schematic block diagram of a general cryptosystem, which illustrates an example of the power analysis attack. Referring to FIG. 1, upon activation of a cryptographic secret key built in a low-power device such as a smart card, an attacker reads a variety of binary code data by detecting an instantaneous voltage (or power) change in an IC chip that is generated from the smart card. The power analysis attack is broadly classified into a simple power analysis (SPA) attack and a differential power analysis (DPA) attack. An SPA attack scheme detects the power consumption of a cryptographic processor operated in a smart card to directly attack a secret key in the smart card. Unlike the SPA attack scheme, a DPA attack scheme uses stochastic analysis and error correction to extract data with an accurate correlation to a secret key from collected power consumption data. In particular, the DPA attack scheme can estimate a secret key merely by using voltage detectors such as an oscilloscope. In addition, the DPA attack scheme can perform not only analysis of important data but also forgery using stochastic analysis.